Do you have any idea who this guy really is? Is he a US citizen or an alien (possibly from an OFAC blocked country)? I don't know that you need to "verify" anything past his statement. He can't provide a valid SSN, evidenced by a SSA card, and admits the number previously provided is fraudulent. I would decline any new account, work towards closing any existing relationship and file a SAR.
Before advising him of your loan decision, I would ask additional questions to try to determmine his country of origin if you think he may be an alien. That might help you know what steps, if any, you need to take to mitigate risk associated with a country under US sanction.
Life without Jesus is like an unsharpened pencil - it has no point.